The National Weather Service issued a weather alert at 11:59 p.m. on Sunday for dense fog until Monday at 6 a.m. for Inner Portland Metro.

"Areas of dense fog will impact mainly parts of Clackamas County in the Portland metro area overnight into early Monday morning. This includes Milwaukie, Lake Oswego, Oregon City, and Happy Valley. Visibility will be reduced to one quarter mile or less at times, and low visibility could make driving conditions hazardous in these locations. Locations within the City of Portland and Multnomah County will mostly remain clear due to east winds out of the Columbia River Gorge. If you encounter dense fog while driving, slow down and leave plenty of distance ahead of you. Pedestrians and cyclists should wear bright or reflective clothing to increase the chances of being seen by others in poor visibility conditions," according to the weather service.

News Source : https://www.oregonlive.com/weather-alerts/2024/12/brace-for-dense-fog-in-inner-portland-metro-until-monday-morning.html